Four-wave Mixing Scheme Research Articles

Stability and bistability of stationary states in four-wave interaction in a photorefractive medium

The stability of stationary states is investigated analytically and numerically for various four-wave mixing schemes in a photorefractive medium with nonlocal nonlinear response when recorded with a translucent grating. Bistability is indicated for a number of four-wave-mixing schemes and the conditions for its existence are indicated.

Squeezed states produced by phase conjugation

The possibility to produce a squeezed state by a phase conjugated mirror is discussed. The quantum noise obtained in a phase conjugated mirror is due to the fact that only the reflected beam is measured. By adding, in interference experiments, the reflected beam to the transmitted one, in a degenerate four-wave mixing scheme, squeezed states are obtained. The possibility to use these phenomena for the production of squeezed states is discussed.

Feedback effects of degenerate four-wave mixing in crystals of the sillenite family

Using the special structure of the electro-optic tensor of the crystals of the sillenite family, Stepanov et al. [ Opt. Acta31, 1335 ( 1984)] suggested a new degenerate four-wave mixing scheme that ensures higher intensities of the phase-conjugate wave. In contrast to Stepanov, we have taken into account the influence of the optical activity and the field-induced birefringence of the sillenite crystals on this phenomenon, which results in good agreement with the experiment. Moreover, the dependence of the so-called positive-feedback scheme on several parameters is discussed.

Observation of 280 nm and 298 nm ultraviolet emissions in sodium vapor

Dye laser output around 578 nm is utilized to pump sodium vapor confined in a heatpipe. Fixed wavelength ultraviolet emissions at 280 nm and 298 nm are observed for the first time and can be explained by anti-Stokes Raman scattering and two photon emission respectively. In addition, there are tunable emission lines around 280 nm and 298 nm, the frequencies of which vary with pump laser wavelength. These tunable lines can be explained by four-wave mixing schemes.

Phase conjugation of CO/sub 2/ laser radiation in a medium with thermal nonlinearity

An investigation of reflectivity and quality of phase conjugation of CO/sub 2/ laser radiation by four-wave mixing in a medium with thermal nonlinearity is discussed. High reflectivity produced by four-wave mixing in CCl/sub 4/ was demonstrated both for pulsed radiation (180%) and for CW radiation (20%). A self-pumped phase-conjugate mirror based on four-wave mixing with feedback was realized. Energy, spatial, spectral, temporal, and polarization characteristics of radiation generated by four-wave mixing with feedback in CCl/sub 4/ were investigated. The minimum threshold energy of the input signal was approximately=8 mJ; the maximum energy reflectivity was about 5. The spatial structure of radiation generated in the scheme of four-wave mixing with feedback was investigated theoretically, and the conditions for phase conjugation, both for regular and for speckled signal beams, were determined. >

Enhancement profile of phase conjugation in plasma by stimulated Brillouin scattering in a four-wave mixing scheme

A quantitative description of the enhancement gain profile of phase conjugation by four-wave mixing in plasma, based on stimulated Brillouin scattering, is presented. The Landau damping mechanism is taken into account, and general geometrical configurations are discussed.

Transient studies of nondegenerate four-wave mixing in a four-level system with saturable absorption and gain

We have investigated a nondegenerate transient four-wave mixing scheme that uses the coupled absorption and emission resonances in a four-level system. Strong frequency-shifted signals can be produced if high initial gain is present. In addition, the medium’s recovery time can be significantly decreased owing to the presence of stimulated emission, which occurs simultaneously with signal generation. Dyes are likely medium candidates.

Tunable VUV light generation for the low-level resonant ionization detection of krypton

High-power tunable VUV light pulses with energies up to 0.7 μJ were generated in the 115.7–116.9-nm region by use of a two-photon resonant four-wave mixing scheme in a Xe–Ar gas mixture. This is the highest reported pulse energy that has been produced in this wavelength region using a four-wave mixing process. Efficient detection of krypton isotopes at densities as low as 10 atoms/cm3 was demonstrated by resonantly ionizing the atom through its one-photon allowed state at the vacuum wavelength of 116.49 nm.

Spatial convolution and correlation of optical fields via degenerate four-wave mixing

A nonlinear optical technique is described that performs, essentially instantaneously, the functions of spatial correlation and convolution of spatially encoded waves. These real-time operations are accomplished by mixing spatially dependent optical fields in the Fourier-transform plane of a lens system. The use of a degenerate four-wave mixing scheme eliminates (in the Fresnel approximation) phase-matching restrictions and (optical) frequency-scaling factors. Spatial bandwidth-gain considerations and numerical examples, as well as applications to nonlinear microscopy, are presented.